The present invention relates to the treatment of ailments in humans and other mammals, and more particularly, to apparatus for delivering pharmaceutical compounds and genes into live cells of a patient.
Somatic cell gene therapy is being pursued in many laboratories. It is known that DNA can be directly injected into certain tissues to cause production of the protein it encodes. This technique may allow physicians to treat human diseases with therapeutic genes. The injected genes may cause the tissues to produce the desired proteins for as long as several months. Most of the current research is focused on the use of marrow stem cells. However, another tissue being considered as a vehicle for gene therapy is the epidermis which is composed mainly of keratinocytes. These cells primarily serve a protective function. However, there is evidence that they may secrete a variety of cytokines and growth factors. See "Prospects for Epithelial Gene Therapy, in: DNA Damage and Repair in Human Tissues", Edited by Sutherland and Woodhead, Plenum Press, New York, 1990, pages 215-223. It appears possible to utilize genetically transformed epithelial cells to treat diseases in distant sites in the body.
U.S. Pat. No. 5,019,034 of Weaver et al. entitled CONTROL OF TRANSPORT OF MOLECULES ACROSS TISSUE USING ELECTROPORATION discloses a method of transporting molecules across tissue which comprises the steps of applying at least one electrical pulse in order to cause electroporation in a region and utilizing a driving force to move molecules across the region. In the specification "driving force" is defined as including iontopheresis, pressure gradients and concentration gradients. The Weaver et al. patent also discloses a method of temporarily increasing the permeability of tissue which comprises applying at least one electrical pulse of sufficient voltage and duration to a region of tissue to cause a reversible electrical breakdown in an electroporated region and wherein the electroporated region is used as a site of molecular transport. The examples given in the Weaver et al. patent all appear to deal with enhanced permeability of samples of skin. Weaver et al. provides only a diagrammatic illustration of an apparatus comprising three inverted U-shaped electrodes 16 in contact with the surface of tissue 22.